The present invention relates to a radio access point testing apparatus, and more particularly to a radio access point testing apparatus which confirms the normalcy of the radio characteristic of a radio access point in an environment where interfering waves such as external noise mix into the radio access point in a mobile communication system employing a CDMA format.
In servicing the mobile communication system, the stability of the system is one of important factors. For the stable operation of the system, it is required to prevent the occurrence of any failure leading to a system service shutdown, and also to promptly detect the failure and resume the system operation in case of the occurrence of the failure. Accordingly, the failure detection of the radio access point and a diagnostic scheme therefor are very important.
As an example of a method for diagnosing the normalcy of the radio access point, JP-A-2002-271280 (Patent Document 1) discloses a method wherein the normalcy of the radio access point is judged in such a way that packet data are transmitted from a maintenance terminal through the Internet to an access terminal which is connected in branch from the antenna of the radio access point, and that a reply from the access terminal is confirmed.
This method is really capable of detecting such an abnormalcy as the complete cutoff of a main signal line in the radio access point apparatus, but it is difficult of detecting such a trifling abnormal state as some degradation in the radio characteristic.
A transmitter and a receiver are mounted in the radio access point. Regarding the failure of the transmitter of them, the degradation of the radio characteristic can be detected comparatively easily by monitoring signal power in a reverse link (in a direction from the access point toward the access terminal). In a forward link (in a direction from the access terminal toward the access point), however, the level of the signal power in a normal condition sometimes becomes a level lower than thermal noise, especially in case of employing the CDMA as a radio communication format, so that the abnormal state is difficult of detection even when the radio characteristic has somewhat degraded.
As a method for solving this problem, a method capable of detecting the abnormal state is disclosed in JP-A-2005-151189 (Patent Document 2). More specifically, a testing access terminal is connected in branch from the antenna port of the radio access point. The testing access terminal controls transmission power so that the packet error rate of sent packets may become constant, and it confirms the transmission power of this testing access terminal at the time when the packet error rate has fallen within a predetermined range. Thus, even when the degradation of the radio characteristic has occurred, the detection of the abnormal state is possible. By way of example, if the transmission power of the testing access terminal is high, degradation in the reception sensitivity of the radio access point is judged.